arch/arm/mm/copypage-v4wb.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/arch/arm/mm/copypage-v4wb.c
   4  *
   5  *  Copyright (C) 1995-1999 Russell King
   6  */
   7 #include <linux/init.h>
   8 #include <linux/highmem.h>
   9
  10 /*
  11  * ARMv4 optimised copy_user_highpage
  12  *
  13  * We flush the destination cache lines just before we write the data into the
  14  * corresponding address.  Since the Dcache is read-allocate, this removes the
  15  * Dcache aliasing issue.  The writes will be forwarded to the write buffer,
  16  * and merged as appropriate.
  17  *
  18  * Note: We rely on all ARMv4 processors implementing the "invalidate D line"
  19  * instruction.  If your processor does not supply this, you have to write your
  20  * own copy_user_highpage that does the right thing.
  21  */
  22 static void v4wb_copy_user_page(void *kto, const void *kfrom)
  23 {
  24         int tmp;
  25
  26         asm volatile ("\
  27         .syntax unified\n\
  28         ldmia   %1!, {r3, r4, ip, lr}           @ 4\n\
  29 1:      mcr     p15, 0, %0, c7, c6, 1           @ 1   invalidate D line\n\
  30         stmia   %0!, {r3, r4, ip, lr}           @ 4\n\
  31         ldmia   %1!, {r3, r4, ip, lr}           @ 4+1\n\
  32         stmia   %0!, {r3, r4, ip, lr}           @ 4\n\
  33         ldmia   %1!, {r3, r4, ip, lr}           @ 4\n\
  34         mcr     p15, 0, %0, c7, c6, 1           @ 1   invalidate D line\n\
  35         stmia   %0!, {r3, r4, ip, lr}           @ 4\n\
  36         ldmia   %1!, {r3, r4, ip, lr}           @ 4\n\
  37         subs    %2, %2, #1                      @ 1\n\
  38         stmia   %0!, {r3, r4, ip, lr}           @ 4\n\
  39         ldmiane %1!, {r3, r4, ip, lr}           @ 4\n\
  40         bne     1b                              @ 1\n\
  41         mcr     p15, 0, %1, c7, c10, 4          @ 1   drain WB"
  42         : "+&r" (kto), "+&r" (kfrom), "=&r" (tmp)
  43         : "2" (PAGE_SIZE / 64)
  44         : "r3", "r4", "ip", "lr");
  45 }
  46
  47 void v4wb_copy_user_highpage(struct page *to, struct page *from,
  48         unsigned long vaddr, struct vm_area_struct *vma)
  49 {
  50         void *kto, *kfrom;
  51
  52         kto = kmap_atomic(to);
  53         kfrom = kmap_atomic(from);
  54         flush_cache_page(vma, vaddr, page_to_pfn(from));
  55         v4wb_copy_user_page(kto, kfrom);
  56         kunmap_atomic(kfrom);
  57         kunmap_atomic(kto);
  58 }
  59
  60 /*
  61  * ARMv4 optimised clear_user_page
  62  *
  63  * Same story as above.
  64  */
  65 void v4wb_clear_user_highpage(struct page *page, unsigned long vaddr)
  66 {
  67         void *ptr, *kaddr = kmap_atomic(page);
  68         asm volatile("\
  69         mov     r1, %2                          @ 1\n\
  70         mov     r2, #0                          @ 1\n\
  71         mov     r3, #0                          @ 1\n\
  72         mov     ip, #0                          @ 1\n\
  73         mov     lr, #0                          @ 1\n\
  74 1:      mcr     p15, 0, %0, c7, c6, 1           @ 1   invalidate D line\n\
  75         stmia   %0!, {r2, r3, ip, lr}           @ 4\n\
  76         stmia   %0!, {r2, r3, ip, lr}           @ 4\n\
  77         mcr     p15, 0, %0, c7, c6, 1           @ 1   invalidate D line\n\
  78         stmia   %0!, {r2, r3, ip, lr}           @ 4\n\
  79         stmia   %0!, {r2, r3, ip, lr}           @ 4\n\
  80         subs    r1, r1, #1                      @ 1\n\
  81         bne     1b                              @ 1\n\
  82         mcr     p15, 0, r1, c7, c10, 4          @ 1   drain WB"
  83         : "=r" (ptr)
  84         : "0" (kaddr), "I" (PAGE_SIZE / 64)
  85         : "r1", "r2", "r3", "ip", "lr");
  86         kunmap_atomic(kaddr);
  87 }
  88
  89 struct cpu_user_fns v4wb_user_fns __initdata = {
  90         .cpu_clear_user_highpage = v4wb_clear_user_highpage,
  91         .cpu_copy_user_highpage = v4wb_copy_user_highpage,
  92 };